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Resolving corrupt probe calibration result

Can anyone advise how to fix a suspect probe calibration result?

I first noticed the positions reported by (2) different probes are off each other by mm.

In the calibration history of the one I see some major change in geometry compared to a few days back.

For a 1MM probe the calibration result went from
T1A0B0 MEAS X 0.180 Y -0.319 Z 236.637 D 1.00 PrbRdv-0.000 StdDev 0.000
to
T1A0B0 MEAS X 3.381 Y 2.000 Z 224.091 D 1.00 PrbRdv-0.000 StdDev 0.000

No matter how many times I recalibrate I can't seem to get it to restore to the original range of values.

And the error in position of a point measured by the (2) probes matches the large non-zero components of this 1mm probe.

Other notes
Often the sphere is not found in the right place and I must answer yes to 'Has the qualification tool been moved'. Yet the sphere has not moved. We only have (1) sphere defined.
I replaced the physical tip but I am sure the geometry of the 1mm probe otherwise did not change.  [I don't see why the Z value changed so much.  Could I have replaced with a slightly shorter/longer tip?]
The SH25-1 plate is sitting properly on the SM25-1 module.

I see the reset tips button available but we have many A, B angles defined. Any ideas?

Parents
  • Well....

    Step one, are you using a master probe, and has it been properly calibrated? (master probe you always select "yes moved")
    Step two are you never selecting "yes moved" for any probe except the master probe? (if so then it's messing things up)

    Reset tips just resets all the measured values to theoretical, it does not erase your angles (just the results from all your angles so you will need a full re-cal)

  • I just started here a month ago and there has been no mention of a Master probe or regular procedure involving same.  They just calibrate required probe(s) immediately before use.

    I was told to try shutting down everything including controller for 30 minutes and reboot.  I'm trying again now. 

    After allowing the machine to do a HOME move and then recalibrating the suspect 1mm probe, the same wild X, Y results are coming

    In the list of all probe names I see no entry resembling 'Master'.

    Thanks for the tips.



  • Do you have a probe rack? 
    Is this your first CMM? 
    We don't judge, we all had to start somewhere! 

  • Got close to 3 years of PC-DMIS under the belt, but hadn't touched it since 2018.

    No probe rack.  All changes done manually.  

    Some probes use SM25-1, some SM25-2.

    There's a small chance I calibrated the 1MM probe with the wrong SM25 unit in place. Disappointed

    Probably need to delete and rebuild the virtual probe?

  • The Master probe is the mathematical correlation between all the probes. It's always perfect, and all other probes are measured in relation to it. This is how the probes maintain their coordinates relative to each other. When you calibrate the probes individually, they are calibrated to themselves, not each other. This is why they don't match. You NEED a master probe. Search this forum. There are lots of posts on this. 

  • without an auto-changer, and ONLY using 1 probe per program, the A0B0 of the probe file is the 'master probe'.  You must always tell it YES that the sphere has moved.

    without an auto-changer, and using MORE THAN 1 probe per program, and doing manual probe changes during the run of the program, the FIRST probe used, A0B0 is the master probe and you must tell it YES the sphere has moved.  Then for any other probes used in the program, you must tell it NO the sphere has not moved.

    OR, you can build a probe and call it MASTER (or any other name you like) and use it to locate the sphere every time you calibrate.  You simply load it up, tell it YES the sphere has moved, the swap to the probe you need and tell it NO, then repeat NO for each probe you need to calibrate for that program.  this MASTER probe can be any probe you already have built, but make a new probe file for it.  if you do make a MASTER probe, keep this in mind, it ALWAYS get the YES answer for if the sphere has moved and the A0B0 should always show ZERO deviation in X, Y, Z, I, J, K.  The only acceptable item that can have a deviation is the SIZE of the probe.

  • Ok.  Thank you. 

    I've been told I'm in charge now, so I can start doing things formally.

Reply Children
  • keep in mind this is ONLY for when you are not un-screwing and screwing new pieces onto it.  Once you un-screw & re-screw, you are basically, well, screwed.

    you need to have modules for each probe build so they stay screwed together all the time.

  • Are you talking about a TP20 or TP200?  I'm using SM25 modules with the magnetic clutches.

    I only unscrew and M2 at the stylus with ruby if it breaks.

    I seem to remember incorrectly using SM25-2 module when SM25-1 was expected, so the SH25-1 probe plate sat crooked.

    Must be other people needing help.   Thank you all.  We'll figure out and I'll post  the solution.

  • TP20, TP200, all the SM modules, etc.  Anything that "magnets on" will work.  TP2, only way to change those old units is to un-screw and screw in new pieces.  OR, if you don't have enough of the magnetic modules that you have to screw a different tip onto it, same issue as the TP2 units

  • It's exciting to be put in charge! 
    Maybe they will let you get a probe rack too! If you have any kind of volume on your machine it will pay for itself quite rapidly.

    If you just use the same few probes in most of your programs then you could calibrate the most common as your "master" then do all angles for the others as "slaves" then you can freely swap between them, also technically with your setup unless you are unscrewing the ruby itself from the black holder you could share modules too between "probes" without the need to recalibrate anything. Buying more holders might be a good option too. 

    Also add a small little white board someplace next to your operator station and keep a record of the current master probe, and any that are slaves to it. (seriously saves the day all the time lol) We had a lil 6" one right on the column so anyone who used the machine would know what was ready to use.